Bartlomiej Obudzinski enhanced the Expensify/App and callstack-internal/Expensify-App repositories by delivering 17 features and resolving 6 bugs over two months, focusing on performance, reliability, and navigation improvements. He unified report action visibility logic, expanded telemetry for performance tracing, and propagated visibility data across UI components using JavaScript and TypeScript. Bartlomiej refactored navigation state management, modularized tab components, and optimized Onyx subscriptions to improve responsiveness and maintainability. His work included rigorous code formatting, linting, and test-driven development, resulting in cleaner, more maintainable codebases and faster feature delivery, while ensuring consistent user experience and robust performance monitoring throughout the applications.